JP3970526B2 - Magnetoresistive element, magnetic reproducing head, magnetic reproducing device, magnetic storage device, and resistance detecting method of magnetoresistive film - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetoresistive effect element using a magnetoresistive effect, a magnetic reproducing head, a magnetic reproducing apparatus equipped with the magnetoresistive effect element, a magnetic storage device, and a resistance detecting method of a magnetoresistive effect film.
[0002]
[Prior art]
In recent years, along with the increase in the density of hard disk drives (HDDs), it has two ferromagnetic layers in which the external magnetic fields are zero and their magnetizations are substantially orthogonal to each other, and a nonmagnetic layer inserted between them. SV-GMR (Spin-Valve Giant Magneto Resistive) heads equipped with a spin valve (SV) film whose electric resistance changes depending on the relative magnetization direction of the magnetic layer have begun to be adopted. In the future, a higher-sensitivity SV-GMR head will be required for further increases in density. Further improvement in magnetoresistive effect change rate (MR change rate) that provides high output, and SV-GMR film thickness In particular, it is important to reduce the thickness of the magnetosensitive layer (magnetization free layer) in which the direction of magnetization changes according to the signal magnetic field.
[0003]
A spin-filter spin-valve (SFSV) film comprising a highly conductive layer adjacent to the magnetization-free layer, which has been made extremely thin to several nanometers, has been proposed and put into practical use. SFSV realizes a high output reproducing head by improving the magnetization sensitivity accompanying the reduction of the thickness of the magnetization free layer.
[0004]
Furthermore, as a technology following SFSV, NOL-SPSV (Nano Oxide Layer-SPecular Spin-Valve) that uses the specular (electron specular reflection) effect to improve MR change rate and has a practical spin valve film structure ) Membranes have been proposed. In this film, an ultra-thin oxide layer called NOL is inserted into a magnetization free layer or a magnetization pinned layer (magnetization pinned layer) stacked via a magnetization free layer and an intermediate nonmagnetic layer. By mirror-reflecting electrons, the spin valve film is made like a pseudo artificial lattice film to increase the MR change rate. By the invention of this structure, it is possible to dramatically improve the MR change rate of the spin valve film.
[0005]
[Problems to be solved by the invention]
However, the present inventors have found that the following problems arise when NOL-SPSV is actually applied to a sensor or a magnetic head.
[0006]
First, using an ultra-thin magnetization free layer is essential for NOL-SPSV films aiming at high-density reproduction, but when using this ultra-thin magnetization free layer, the bias point (operating point during head operation) is adjusted. Becomes difficult. For this purpose, it is important to reduce various magnetic fields applied to the magnetization free layer. Among them, the leakage magnetic field (Hpin) of the magnetization pinned layer greatly affects the magnetization of the magnetization free layer.
[0007]
In order to reduce the leakage magnetic field of this magnetization pinned layer, in SFSV, Sy is obtained by synthetic coupling (antiferromagnetic coupling, hereinafter referred to as Sy-AF) between two ferromagnetic layers laminated via a nonmagnetic layer. -The AF structure is adopted for the magnetization pinned layer.
[0008]
In this Sy-AF structure, the upper and lower ferromagnetic pinned layers sandwiching the nonmagnetic layer such as Ru having an average film thickness of about 9 angstroms are antiferromagnetically coupled. Therefore, the leakage magnetic field from the magnetization pinned layer is the difference between the upper and lower pinned layer magnetic film thicknesses (Ms x t (saturation magnetization x film thickness)), and is substantially applied to the magnetization free layer without making the magnetization pinned layer extremely thin. The pin layer leakage magnetic field can be lowered. Details of the Sy-AF structure are disclosed in Japanese Patent Publication No. 2786660.
[0009]
In this way, while reducing the leakage magnetic field of the magnetization pinned layer, by using a highly conductive layer such as a Cu layer, the current magnetic field (H_cu) And an indirect interlayer coupling magnetic field (H between the magnetization free layer and the pin layer via the nonmagnetic spacer layer)._in)_pin+ H_cu+ H_inBy selecting the current direction so that the relationship of = 0 holds, SFSV using the Sy-AF structure has realized a good bias point.
[0010]
However, when attempting to realize the Sy-AF structure in the NOL-SPSV film, the problem that the above-mentioned characteristics of the Sy-AF structure are not obtained has been clarified. Although the detailed reason is not clear, for example, oxygen, nitrogen, fluorine, carbon, etc. in the NOL layer diffuse into the Ru layer of the Sy-AF structure by heat treatment, and antiferromagnetic coupling of the upper and lower magnetization pinned layer via Ru This is thought to be caused by a phenomenon such as weakening. As a result, the Sy-AF structure cannot be adopted in the NOL-SPSV, and the leakage magnetic field from the magnetization pinned layer cannot be reduced, so that a good bias point cannot be realized.
[0011]
On the other hand, there is a concept of using a magnetic keeper layer in order to cancel the leakage magnetic field from the magnetization pinned layer completely to zero (Japanese Patent Laid-Open No. 8-55312). This is because a soft magnetic keeper layer is laminated on either the upper or lower surface of the spin valve film, and the magnetization direction of the soft magnetic keeper layer is opposite to the magnetic field direction of the magnetization pinned layer by a current magnetic field. This cancels the layer leakage magnetic field.
[0012]
This cancellation method using a magnetic keeper layer completely eliminates the pin layer leakage magnetic field and_inH_cuTo cancel with (H_in= H_cu, H_pin= 0) to adjust the bias point. In relatively low density recording, since the magnetization free layer is thick, the external magnetization sensitivity of the magnetization free layer is dull. In addition, since the magnetization free layer is thick, the ratio of the conductance of the magnetization free layer in the SV film of the magnetization free layer is large, so that the current magnetic field becomes relatively small, which is reduced by the small interlayer coupling magnetic field H._inThe canceling method using the magnetic keeper layer is effective.
[0013]
However, the film thickness of the magnetization free layer of NOL-SPSV, which aims at high recording density, is expected to decrease._cuTherefore, there is a limit to the cancellation method using the magnetic keeper layer.
[0014]
Note that it is easy to see from the film structure described in the above publication that the current magnetic field is not too large. In other words, in order to reduce the current magnetic field to the magnetization free layer in SFSV described above, it is essential for the high-density head to reduce the current magnetic field by forming a highly conductive layer in contact with the magnetization free layer. This is because there is no description in JP-A-8-55312.
[0015]
In addition, H_inA method of realizing a bias point by flowing a current in the direction of canceling is not realistic in NOL-SPSV. That is, the current magnetic field H_cuIs H_inBigger than H_in= H_cuThis design is very difficult.
[0016]
Thus, with the conventional bias point adjustment method, it is difficult to satisfactorily adjust the bias point of NOL-SPSV.
[0017]
The present invention, beginning with the problems in the prior art described above, includes a magnetoresistive effect element having a good bias point, a magnetoresistive effect head, a magnetic reproducing device equipped with the magnetoresistive effect device, a magnetic storage device, and a magnetoresistive effect film. It is an object to provide a resistance detection method.
[0018]
[Means for Solving the Problems]
  In order to solve the above problems, an embodiment of the present invention provides a first ferromagnetic material having magnetization in a first direction when an applied magnetic field is zero and capable of rotating the magnetization under a predetermined applied magnetic field. A first nonmagnetic layer formed on the first ferromagnetic layer, and a first nonmagnetic layer formed on the first nonmagnetic layer, wherein the applied magnetic field is zero and the predetermined applied magnetic field is And a second ferromagnetic layer that retains magnetization in the second direction;Formed between the second ferromagnetic layer and the second nonmagnetic layer and in contact with the second ferromagnetic layerAn antiferromagnetic layer, a second nonmagnetic layer formed on the antiferromagnetic layer, and a layer formed on the second nonmagnetic layer, the magnetization pinning direction being opposite to the second direction And formed in the third ferromagnetic layer made of a soft magnetic material and the second ferromagnetic layer or between the second ferromagnetic layer and the second nonmagnetic layer, A magnetoresistive film including a layer containing oxide, nitride, carbide, or fluoride, and the direction of the current magnetic field in the third ferromagnetic layer is opposite to the second direction. Provided is a magnetoresistive element comprising a pair of electrodes for passing a current through a magnetoresistive film.
[0019]
Further, the magnetoresistive element can constitute a magnetic reproducing head mounted on a head gimbal assembly or the like. In addition, a magnetic reproducing apparatus equipped with this magnetic reproducing head and a magnetic recording medium on which magnetic information is recorded can realize higher recording density than ever before. The magnetoresistive element of the present invention can also be used for a magnetic reproducing apparatus in which a magnetic recording medium can be removed.
[0020]
In addition, the magnetoresistive element can constitute a memory cell together with a transistor or a diode or independently. By integrating the magnetoresistive elements, a nonvolatile semiconductor memory device can be configured.
[0021]
  Furthermore, another embodiment of the present invention comprises a first ferromagnetic layer having a magnetization in a first direction when the applied magnetic field is zero, and wherein the magnetization can rotate under a predetermined applied magnetic field, A first nonmagnetic layer laminated on the first ferromagnetic layer, and a second nonmagnetic layer laminated on the first nonmagnetic layer, wherein the applied magnetic field is zero and the second applied under the predetermined applied magnetic field. A second ferromagnetic layer that retains magnetization in the direction ofFormed between the second ferromagnetic layer and the second nonmagnetic layer and in contact with the second ferromagnetic layerAn antiferromagnetic layer, a second nonmagnetic layer formed on the antiferromagnetic layer, and a layer formed on the second nonmagnetic layer, the magnetization pinning direction being opposite to the second direction And formed in the third ferromagnetic layer made of a soft magnetic material and the second ferromagnetic layer or between the second ferromagnetic layer and the second nonmagnetic layer, A magnetoresistive film including an oxide, nitride, carbide, or fluoride-containing layer, and passing a current in a direction in which a current magnetic field in the third ferromagnetic layer is opposite to the second direction. The present invention relates to a method for detecting a resistance of a magnetoresistive film, wherein the resistance value of the magnetoresistive film is detected.
[0022]
In the magnetoresistive effect element, the magnetic reproducing head, the magnetic reproducing device, and the resistance detecting method for the magnetoresistive film described above, the following configuration can be provided.
1. The first ferromagnetic layer has a third nonmagnetic layer containing any element of Cu, Au, and Ag formed on the surface opposite to the surface in contact with the second nonmagnetic layer. The content may be a nonmagnetic layer containing 50 atomic% or more.
2. The average film thickness of the first ferromagnetic layer is 3 nm or less.
3. The magnetic thickness of the third ferromagnetic layer is 1.8 nmT or more and 4.5 nmT or less in terms of the material of saturation magnetization 1T.
4). The third ferromagnetic layer contains a CoFe alloy of 50 atomic% or more, and the average film thickness is 1 nm or more and 2.5 nm or less.
5. The average film thickness of the layer containing oxide, nitride, carbide, or fluoride is 1 nm or more and 2 nm or less. The oxide, nitride, carbide, or fluoride content of this layer can be 50 atomic% or more.
6). The direction of the leakage magnetic field applied from the third ferromagnetic layer to the first ferromagnetic layer is such that the leakage magnetic field from the second ferromagnetic layer, the current magnetic field, and the first magnetic layer are applied to the first ferromagnetic layer. This is a direction to cancel the direction of the magnetic field obtained by the sum of the interlayer coupling magnetic fields due to the interlayer coupling between the first ferromagnetic layer and the second ferromagnetic layer.
7. An antiferromagnetic layer formed between the second ferromagnetic layer and the second nonmagnetic layer and in contact with the second ferromagnetic layer.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
Next, a magnetoresistive effect element according to one embodiment of the present invention will be described.
[0024]
First, a magnetoresistive effect element of this form includes a first ferromagnetic layer having a magnetization in a first direction with an applied magnetic field being zero, and capable of rotating the magnetization by a predetermined applied magnetic field, and a first strong layer. A first nonmagnetic layer laminated on the magnetic layer and a nonmagnetic intermediate layer, and a second strong magnetic field that maintains magnetization in the second direction in a state where the applied magnetic field is zero and the predetermined applied magnetic field. A magnetic layer is provided.
[0025]
The first ferromagnetic layer is a magnetization free layer whose magnetization rotates when an applied magnetic field such as a signal magnetic field is applied. This magnetization free layer is laminated with the second ferromagnetic layer via a spacer layer containing Cu or the like as the first nonmagnetic layer. This second ferromagnetic layer is a magnetization pinned layer that maintains its magnetization direction even in a state where the applied magnetic field is zero and a predetermined applied magnetic field in which the magnetization of the first ferromagnetic layer rotates.
[0026]
The magnetization pinning (pinning) of the magnetization pinned layer in the second direction is a method using a ferromagnetic material having a coercive force high enough to maintain magnetization even in a predetermined applied magnetic field as a material of the magnetization pinned layer. There are a method of stacking with a ferromagnetic layer and fixing it by magnetic exchange coupling with an antiferromagnetic layer, and a method of fixing a hard magnetic layer close to or adjacent to the magnetization pinned layer and fixing it by its leakage magnetic field.
[0027]
The first and second directions may be the same, but are preferably different, and may be substantially perpendicular to each other. An element in which the first and second directions are substantially perpendicular is a so-called spin valve element.
[0028]
The electric resistance of the magnetoresistive effect element is low when the magnetization of the magnetization free layer changes according to the signal magnetic field and is equal to the second direction, and the magnetization of the magnetization free layer is substantially antiparallel to the second direction. It shows high resistance in the state.
[0029]
Such a resistance change is due to the fact that electrons are scattered depending on the magnetization (spin) direction of the ferromagnetic layer at the interface between the ferromagnetic layer of the magnetization free layer and the magnetization pinned layer and the nonmagnetic spacer layer. Yes (spin-dependent interface scattering).
[0030]
In the present embodiment, an oxide, nitride, or carbide formed in the layer of the magnetization pinned layer of such a magnetoresistive effect element or on the surface opposite to the side in contact with the nonmagnetic spacer layer of the magnetization pinned layer. Or a layer containing fluoride. This layer mirror-reflects (specular) electrons that have moved through the magnetoresistive effect element. For electrons that have passed through the magnetization pinned layer from the nonmagnetic spacer layer and reached the mirror surface of this layer, the nonmagnetic spacer layer The interface between the magnetization pinned layer and the magnetization free layer increases in a pseudo manner, and the number of scattering can be increased.
[0031]
The average film thickness of the oxide, nitride, carbide, or fluoride-containing layer is about 0.5 nm to 5 nm from the viewpoint of setting the magnetic coupling force between the magnetic layers sandwiching the average value. preferable. Hereinafter, this layer is referred to as NOL, taking as an example a layer comprising an oxide as a main component.
[0032]
The NOL-SPSV of this embodiment newly includes a third ferromagnetic layer as a BCL (Bias Compensation Layer) that compensates for an external magnetic field (bias) applied to the magnetization free layer. A soft magnetic material or the like is preferable for the BCL.
[0033]
Due to the leakage magnetic field applied from the BCL to the magnetization free layer, due to the leakage magnetic field from the magnetization pinned layer, the current magnetic field generated by current conduction, and the interlayer coupling between the magnetization pinned layer and the magnetization free layer. The bias point of this magnetoresistive element is adjusted by canceling the sum of the interlayer coupling magnetic fields. That is, the magnetization direction of the magnetization free layer when the applied magnetic field is zero can be set to a desired first direction.
[0034]
In order to adjust the bias point, it is necessary to pass a current so that the direction of the current magnetic field in the BCL is opposite to the magnetization direction (second direction) of the magnetization pinned layer.
[0035]
The second nonmagnetic layer is necessary to prevent magnetic coupling between the magnetization pinned layer and the BCL.
[0036]
Such a favorable bias point in NOL-SPSV can be realized by the present embodiment as a result of the inventors' research as described below. The details will be described below.
[0037]
First, the interlayer coupling magnetic field H applied to the magnetization free layer by interlayer coupling with the magnetization pinned layer_inThe leakage magnetic field H from other ferromagnetic layers_pAnd current magnetic field H_cuIs the main magnetic bias applied to the magnetization free layer and the bias point is adjusted (H_p= H_cu+ H_inHowever, if the magnetization pinned layer and the magnetization free layer have a ferromagnetic magnetization arrangement, H_inIs a positive value, H in the case of an antiferromagnetic magnetization array_inIs a negative value), which seems to be the most realistic method for high-density playback.
[0038]
  That is, magnetismConversionThe bias point is adjusted so that Hp and Hcu, which are static magnetic fields to the free layer, are reversed. The value of Hp is solved by using the bias compensation effect by BCL.
[0039]
That is, the leakage magnetic field H applied from the BCL to the magnetization free layer^BCLThe leakage magnetic field H applied from the magnetization pinned layer to the magnetization free layer^pinAnd in the opposite direction, H_p It solves the increase of
[0040]
The concept of bias point adjustment in the present invention is shown in the following equation.
[0041]
H_p = H_in + H_cu(1)
H_p = H^pin ― H^BCL                       (2)
However, H_inSign of H_cuIs defined as positive.
[0042]
H^pin= π²(Ms × t)_pin/ h (3)
H_cu= 2πc × I_s/ h (4)
c = | (I₁-I_Three) / (I₁+ I₂+ I_Three) | (5)
H^BCL= D × π²(Ms × t)_BCL/ h (6)
In the above formulas (1) to (6), h is the MR height [μm]. D is a value smaller than 1 and varies depending on the sense current value and the value of Ms × t of the magnetization pinned layer. In other words, the larger the sense current value is, and the larger the value of Ms × t of the magnetization pinned layer is, the larger D is, which approaches 1.
[0043]
I_sIndicates the sense current value flowing in the magnetoresistive film, and the shunt value I₁, I₂And I_ThreeIndicates the sum of These current values indicate the current value flowing in each region obtained by dividing the region in which the current flows by the pair of electrodes in the magnetoresistive effect film into three in the vertical direction, and the current value I flowing in the magnetization free layer that is the middle region.₂The current value I flowing through the region from the upper layer of the magnetization free layer to the uppermost conductive layer (cap layer 27 in FIG. 1) between the electrodes₁, And the current value I flowing through the region from the lower layer of the magnetization free layer to the lowermost conductive layer (buffer layer 3 in FIG. 1) between the electrodes._ThreeIt is. Note that Is is a positive value when a current flows in a direction in which the current magnetic field in the BCL 7 is opposite to the magnetization direction of the magnetization pinned layer.
[0044]
The adjustment of the bias point using BCL will be described below using a specific structure as an example.
[0045]
FIG. 1 shows a schematic cross-sectional structure of the bottom type spin valve film of the present embodiment.
[0046]
The magnetoresistive effect element according to the present embodiment includes a buffer layer 3, a seed layer 5, a BCL 7, a BCL 7, a decoupling layer 9 that prevents magnetic coupling between the antiferromagnetic layer 11 and an antiferromagnetic layer, which are sequentially formed on the substrate 1. Magnetoresistive film 28 including layer 11, magnetization pinned layer 13, NOL15, magnetization pinned layer 17, nonmagnetic layer 19, magnetization free layer 21, HCL23, NOL25, cap layer 27, a pair of hard bias films 29, a pair of leads An electrode 31 is provided. The materials constituting the main component of each layer will be described in detail in Example 1.
[0047]
In the bottom type spin valve film in which the magnetization pinned layer is positioned below the magnetization free layer in the stacking direction, the BCL is disposed below the magnetization pinned layer. In the top type spin valve film in which the magnetization pinned layer is positioned above the magnetization free layer in the stacking direction, the BCL is disposed above the magnetization pinned layer.
[0048]
In FIG. 1, the antiferromagnetic layer 11 is exchange-coupled to the magnetization pinned layer 13, and the magnetization direction of the magnetization pinned layer 13 is fixed in the direction from the back to the front of FIG. Has been. Further, the magnetization pinned layer 17 has magnetization in the same direction as the magnetization pinned layer 13 due to ferromagnetic exchange coupling with the magnetization pinned layer 13.
[0049]
  The NOL 15 between the magnetization pinned layers 13 and 17 contains an oxide of the material constituting the magnetization pinned layer 13 as a main component (50 atomic% or more).ConversionA specular reflection effect on the surface on the pinned layer 17 side can be expected. The main component of NOL 15 can be appropriately changed to carbide, nitride, fluoride, etc. in addition to oxide. Further, it may be an oxide, carbide, nitride, or fluoride of a material different from the material constituting the magnetization pinned layer 13.
[0050]
The nonmagnetic layer 19 in contact with the magnetization pinned layer 17 is a nonmagnetic spacer layer of the spin valve element, and spin-dependent scattering occurs on both surfaces in contact with the magnetization pinned layer 17 and the magnetization free layer 21 of this layer.
[0051]
The magnetization free layer 21 is given a magnetization bias in the left-right direction in FIG. 1 by a leakage magnetic field from a pair of hard bias films 29 formed on both sides by a so-called abut junction structure. When the external magnetic field is zero, , Has magnetization in this direction. In addition, this magnetization bias maintains a single magnetic domain in the magnetization free layer 21, and measures against Barkhausen noise are taken.
[0052]
The magnetization free layer 21 is adjusted so that its magnetization can freely rotate when an external magnetic field is applied. When an external magnetic field in the reverse direction is applied from the front and back of FIG. The magnetization of the layer 21 changes following this direction. On the other hand, when an external magnetic field in the front direction is applied from the back of the sheet of FIG. 1, the magnetization of the magnetization free layer 21 also changes following this direction.
[0053]
Due to the magnetization rotation of the magnetization free layer 21, the electric resistance of the magnetoresistive effect film 28 changes depending on the relationship that the relative magnetization direction with the magnetization pinned layer 17 is parallel or antiparallel. That is, the electrical resistance of the magnetoresistive film 27 is low when the magnetization directions are parallel, and the electrical resistance of the magnetoresistive film 27 is high when the magnetization directions are antiparallel. This change in electrical resistance is detected by a conventionally known detection circuit that detects a change in resistance via a pair of lead electrodes 31 connected to both ends of the magnetoresistive film.
[0054]
An HCL 23 containing a highly conductive material is formed on the magnetization free layer 21, and as described above, the HCL 23 is adjusted by adjusting its thickness._cuCan be adjusted as appropriate.
[0055]
The NOL 25 on the HCL 23 is inserted with the intention of an electron mirror reflection effect on the magnetization free layer 21 side.
[0056]
The method for maintaining the bias point in the magnetoresistive film 28 is as described in the above basic formula.
[0057]
The relationship between the above equations (1) and (2) and the structure of this element will be described with reference to FIG.
[0058]
The cross-sectional structure of the magnetoresistive element shown in the cross-sectional perspective view of FIG. 2 is the same as that of FIG. However, for convenience, FIG. 2 shows the magnetoresistive film 28 of FIG. 1 further enlarged in the vertical direction of the drawing.
[0059]
It is important for adjusting the bias point to adjust so as to sufficiently satisfy the expression (1). Variable factors include H_pAnd H_cuIs used. H_cuAs described above, it can be changed by controlling the film thickness of a nonmagnetic high conductive layer (HCL) formed adjacent to the magnetization free layer.
[0060]
In other words, the thicker the HCL film, the more the current magnetic field H_cuBecomes smaller and H increases due to film thickness increase._cuThe degree of reduction increases as the sheet resistance of the magnetoresistive film 28 increases.
[0061]
In simple terms, the degree of the effect can be calculated by approximating each layer of the spin valve film with a parallel conductor model. However, in this case, the specific resistance value of each layer should not be calculated using the bulk value, but should be calculated from the amount of change in conductance when shifted from 1 nm to 2 nm in the positive or negative direction from the actual film thickness. is required. By this method, it can be used approximately as a specific resistance value in consideration of the current Boltzmann distribution.
[0062]
Next, H_pIs H, as in equation (2).^pinAnd H^BCLAnd determined from
[0063]
Of which, H^pinIs roughly determined by the height of the magnetization pinned layers 13 and 17 (the height extending from the signal inflow surface of the magnetoresistive effect film 28 to the back) and the magnetic film thickness (Ms × t).
[0064]
However, for the sake of simplicity, it is assumed that the magnetization directions of the magnetization pinned layers 13 and 17 are completely fixed in one direction. In FIG. 1, it is necessary to consider that they are not fixed in the direction from the back to the front of the paper. For example, in a shield type head in which the magnetoresistive film 28 is sandwiched by a shield film through a gap film, a shield film is provided at the end in the track width direction (left and right direction in FIG. 1). This is because bending (curling) exists and the magnetization direction is deviated from the desired direction by a bias magnetic field from the hard bias film 29 for making the magnetization free layer a single magnetic domain.
[0065]
In FIG. 2, H^BCLIs the leakage magnetic field applied to the magnetization free layer by BCL, and the current magnetic field H in BCL_cu ^BCLAnd leakage magnetic field H from the magnetization pinned layers 13 and 17_pin ^BCLOf the sum of BCL is likely to receive a current magnetic field in the magnetoresistive effect film 28 as much as possible (from the upper and lower ends from the current center position), and the current magnetic field in the BCL (H_cu ^BCL) Is the direction of the current magnetic field (H_cu) In the opposite direction. This causes H_p= H^pin+ H^BCLCan be realized, and a good bias point in NOL-SPSV can be realized.
[0066]
On the other hand, H in equation (2)^BCLIs a factor newly introduced in the present invention.
[0067]
BCL consists of a ferromagnetic layer, and its magnetization pinned direction is opposite to the magnetization direction of the magnetization pinned layer. This is because the current magnetic field (H_cu ^BCL) And leakage magnetic field (H_pin ^BCL) In the same direction. Therefore, H^BCLH_cu ^BCL+ H_pin ^BCLBy adjusting these magnetic fields appropriately, H^BCLCan be determined.
[0068]
The direction of the sense current passed through the electrode 31 is the current magnetic field (H_cu) Is applied to the magnetization free layer from other ferromagnetic layers such as the magnetization pinned layer (H_p) Is the direction to cancel.
[0069]
As described above, the magnetization of the BCL is fixed by the current magnetic field and the leakage magnetic field from the magnetization pinned layer, but as described above, the magnetization direction of the magnetization pinned layer is not completely fixed in the MR height direction. , H_pin ^BCLTends to be smaller than a pinned layer using Sy-AF. Further, H by the hard bias film 29_pin ^BCLThe effect of reduction is more noticeable in BCL using a soft magnetic layer, so it is desirable to take these into consideration when designing.
(Example 1)
In Example 1, Example 1 of the bottom type spin valve film according to the first embodiment will be described.
[0070]
First, a spin valve film composed of the following layers was formed on the substrate 1. The film thickness is a value immediately after film formation by controlling the film formation speed and film formation time.
[0071]
Ta 3nm / NiFeCr 2nm / CoFe 1.5nm / NiFeCr 1nm / PtMn 10nm / CoFe 0.5nm / NOL / CoFe 2nm / Cu 2.3nm / CoFeNi 2nm / Cu 1nm / TaO 1nm
The spin valve film was formed by DC magnetron sputtering in vacuum using the layer material of each layer as a target material. Ultimate vacuum in the sputter chamber is 1 × 10^-7The film was formed at a gas pressure of 1 mTorr to 10 mTorr using Ar gas at a pressure lower than Torr. In addition to the DC magnetron sputtering method, an IBD (Ion Beam Deposition) method may be used. In that case, Xe gas can be used as the sputtering gas, and the gas pressure can be lowered as compared with DC magnetron sputtering.
[0072]
Next, the configuration of each layer will be described with reference to FIG.
[0073]
From the substrate 1 side, the Ta layer is the buffer layer 3, and an average film thickness of about 0 to 5 nm is desirable. Instead of Ta, metals such as Ti, Zr, Hf, W, Cr, V, Mo, Re, Os, and alloys thereof may be used. Of these, Ta, Ti, and Zr can be used.
[0074]
The NiFeCr layer thereabove is a seed layer 5 made of a non-magnetic material that promotes parallel orientation with respect to the layer surface of the (111) plane of the face-centered cubic structure (fcc) of CoFe, NiFeCr, etc. of the upper layer. Here, Cr is added to reduce the shunt and to make the magnetic material NiFe nonmagnetic. The addition amount of Cr is desirably about 20% to 60% (atomic%). Further, Nb, Hf, Ta, Ti, Mo, W or the like may be added instead of chromium. Furthermore, nonmagnetic NiCr, Cu, Ru, Re, Os, Pt, nonmagnetic NiCu, or the like may be used as the fcc (111) orientation promoting film. If the seed layer 5 is made of a material having a crystal orientation promoting function, the buffer layer 3 may be omitted.
[0075]
The CoFe layer on the NiFeCr layer is BCL7 and is fcc (111) -oriented due to the effect of the underlying seed layer._cu ^BCLAnd leakage magnetic field H from the magnetization pinned layers 13 and 17_pin ^BCLTherefore, the magnetization direction can be opposite to the magnetization direction of the magnetization pinned layer.
[0076]
If the soft magnetism of BCL7 is not enough, current magnetic field (H_cu ^BCL) And the leakage magnetic field (H_pin ^BCL) Is not preferable because the magnetization direction does not move. However, soft magnetism is not required as much as the magnetization free layer 21 that must react sensitively to the medium magnetic field.
[0077]
One standard is the current magnetic field (H_cu ^BCL) And leakage magnetic field from pinned layer (H_pin ^BCLAs long as the coercive force (Hc) is 1/10 to 1/5 or less, there is no problem. Since this film plays an important role for bias point control, it is necessary to pay attention to this film thickness determination. The guideline for determining the film thickness will be described in detail later.
[0078]
The sputtering target material for BCL7 is CoFe here, but it can be a crystalline material such as NiFe or NiFeX (X = Cr, Nb, Hf, Ti, Ta, W, Mo), or an amorphous material such as CoZrNb or CoZrTa. I do not care. However, in the case of the bottom type NOL-SPSV, the BCL 7 also has a role as an underlayer, and therefore, a crystal material such as CoFe or NiFe is desirable in terms of controlling crystal orientation laminated on the BCL 7. When the BCL 7 is a top type located in the upper layer in the spin valve film, an amorphous material may be used.
[0079]
The NiFeCr layer on the CoFe layer is a nonmagnetic layer (decoupling layer 9) for breaking the magnetic coupling between the magnetic BCL 7 and the antiferromagnetic layer 11 PtMn layer. Since the smaller one is better, the same NiFeCr as the seed layer 5 was used. The material is not necessarily the same as that of the seed layer 5, but the materials just mentioned for the base seed layer can be used as they are.
[0080]
Here, there is a problem if magnetic coupling occurs between the antiferromagnetic film 11 and the BCL 7. This is because, as shown in FIG. 1, the magnetization direction of the magnetization pinned layers 13 and 17 fixed by exchange coupling with the antiferromagnetic film 11 and the leakage magnetic field (H_pin ^BCL) And current magnetic field (H_cu ^BCL), The magnetization direction (H^BCL= H_pin ^BCL+ H_cu ^BCLHowever, if magnetic coupling occurs between the BCL 7 and the antiferromagnetic layer 11, the magnetization directions of the magnetic pinned layers 13 and 17 and the magnetization direction of the BCL 7 are the same direction. This is because the action to become works.
[0081]
When the coupling between the BCL 7 and the antiferromagnetic layer 11 occurs, it is necessary to make the current magnetic field applied to the BCL 7 or the magnitude of 1/10 to 1/5 or less of the leakage magnetic field from the magnetization pinned layer 17. Therefore, the necessary NiFeCr film thickness is desirably about 0.5 nm to 5 nm, and more desirably about 1 to 3 nm. The thicker it is, the more magnetic coupling can be cut off. However, the electrical shunt increases, and the total film thickness also increases, so adjustment with a high narrow gap (high density) is required. Is required. Further, when used in a reproducing magnetic head, it is difficult to put a thick spin valve film between the magnetic shields via a magnetic gap, so the above film thickness range is preferable.
[0082]
The PtMn layer on the NiFeCr layer is the antiferromagnetic layer 11 and fixes the magnetization of the magnetization pinned layer (CoFe layer) 13 laminated thereon. In order to reduce the electrical shunt, it is desirable that the antiferromagnetic layer 11 is thin. However, if it is too thin, magnetization fixation in one direction becomes difficult. Therefore, in the case of PtMn, about 6 nm to 20 nm is desirable, and further desirable. Is preferably about 8 nm to 15 nm.
[0083]
The antiferromagnetic layer 11 is preferably PtMn, but PdPtMn, IrMn, RuMn, RuRhMn, NiMn, NiO, α-Fe instead of PtMn.₂O_ThreeFor example, another antiferromagnetic layer having a function of fixing the magnetization direction in one direction may be used.
[0084]
CoFe / NOL / CoFe on the PtMn layer is a magnetization pinned layer with an integral magnetization direction, and the upper and lower CoFe via the NOL are ferromagnetic enough to be magnetically strong even when a signal magnetic field is applied. Are connected. The CoFe layer in contact with the PtMn layer preferably has a thickness necessary to prevent oxygen from NOL from reaching PtMn and to magnetically couple with the PtMn layer. However, it is preferable that the thickness is as thin as possible so that the influence of oxygen by NOL15 does not reach the PtMn layer and can be coupled with the PtMn layer at the same time.
[0085]
In addition, since the magnetic film thickness of the magnetization pinned layers 13 and 17 is likely to increase with NOL-SPSV, it is desirable that the magnetic film thickness of the magnetization pinned layers 13 and 17 is as small as possible. For example, it is also desirable to add an additive element such as Cr, B, or Cu in order to reduce the saturation magnetization. The film thickness here is CoFe 0.5 nm, but about 0.3 nm to 1.5 nm is desirable. The magnetic material here may be Fe, Fe-based alloy, Ni, Ni alloy or the like in addition to CoFe alloy. For example, CoFeCr, CoFeB, CoFeCu, etc. can be used.
[0086]
The NOL 15 can be formed by oxidizing the surface on which the magnetization pinned layer 13 is formed, and an oxide film can also be formed.
[0087]
Methods for oxidizing the metal surface include oxygen flow in ultra-high vacuum, plasma oxidation, UV oxidation, and oxidation by an oxygen ion beam. At this time, it is necessary to take care not to oxidize the antiferromagnetic layer 11 below the magnetization pinned layer 13.
[0088]
As a method for forming an oxide film, there are a method in which an oxide target is formed by sputtering, a method in which a metal target is sputtered in an oxygen atmosphere, and a method by reactive sputtering. The film thickness of this NOL 15 is desirably about 0.1 nm or more and about 5 nm or less. Particularly desirably, the thickness is about 1 nm or more and about 2 nm or less. Since the magnetization pinned layer 17 formed on the NOL 15 is a ferromagnetic layer that greatly affects the MR change rate, it is desirable not to add too many additional elements even when the magnetization pinned layer 17 has a low magnetic film thickness.
[0089]
Desirably, Co or a CoFe alloy may be used, and a NiFe alloy may be used. When B and Cu are added to the CoFe alloy to reduce Bs, a small amount of addition can be 3 to 10 atomic%.
[0090]
The Cu layer formed on the magnetization pinned layer 17 is a nonmagnetic layer 19, and a film thickness of about 1.5 nm to about 3 nm is desirable. Particularly desirable is from about 2 nm to about 2.5 nm. When the film thickness of the nonmagnetic layer 19 and the flatness of the layer surface are deteriorated, the magnetic field strength of the inter-layer coupling between the magnetization free layer 21 and the magnetization pinned layer 17 increases. Is important.
[0091]
Normally, the magnetization pinned layer 17 and the magnetization free layer 21 often have a ferromagnetic magnetization arrangement, but there may be antiferromagnetic magnetization arrangement coupling. Either way, too big H_inIt is desirable not to be the value of. H_inThe value of is preferably about −20 Oe or more and about +20 Oe or less (when +, the magnetization pinned layer and the magnetization free layer are ferromagnetic magnetization arrangements, and when − is an antiferromagnetic magnetization arrangement). More desirably, about −10 Oe to about +10 Oe is preferred.
[0092]
A CoFeNi layer that forms the magnetization free layer 21 is formed on the Cu layer. As the configuration of the magnetization free layer 21, a CoFe / NiFe laminated free layer in which CoFe is in contact with the nonmagnetic layer 19, a single layer CoFe free layer, a single layer CoFeNi free layer, or the like can be used. The single-layer CoFeNi layer used in Example 1 realizes control of magnetostriction and good soft magnetism by adding Ni.
[0093]
In order to utilize the specular electron reflection effect by the NOL 25, it is preferable that the magnetization free layer 21 is thin. Specifically, it is preferably about 1 nm or more and about 4 nm or less, more preferably about 1.5 nm or more and about 3 nm or less.
[0094]
The Cu layer stacked on the magnetization free layer 21 is the HCL 23 and has an effect of adjusting the bias point. In other words, the current magnetic field H applied to the free layer by bringing the current center flowing in the spin valve film closer to the magnetization free layer from the magnetization pinned layer side by the Cu layer._cuCan be reduced.
[0095]
However, it is not preferable to make the HCL 23 too thick because the MR change rate is reduced by the shunt. A desirable range is about 0.3 nm or more and about 3 nm or less, more preferably about 0.5 nm or more and about 2 nm or less.
[0096]
The film thickness of the HCL 23 greatly depends on the bias point, and should be changed in accordance with the magnitude of the magnetization pinned layer leakage magnetic field Hpin. The film thickness of the HCL 23 will be described later together with the BCL film thickness.
[0097]
The TaO cap layer 27 on the Cu layer has a specular reflection effect, and is preferably an oxide layer. The material may be other metal oxides such as AlO, TiO, CrO, WO, VO, ZrO, HfO, FeO, and CoO other than TaO. Further, a metal Ta layer may be further formed on the oxide layer as a cap layer.
[0098]
In this embodiment, the bottom type spin valve in which the magnetization pinned layers 13 and 17 are located below the magnetization free layer 21 has been described. However, the present invention is not limited to the bottom type, and the magnetization pinned layer is not limited to the bottom type spin valve. A top type formed above the magnetization free layer may be used.
[0099]
The top type includes TaO / Cu 1 nm / NiFe 1 nm / CoFe 1 nm / Cu 2.2 nm / CoFe 2 nm / NOL 1.5 nm / CoFe 0.5 nm / PtMn 10 nm / NiFeCr 1 nm / CoFe 1.5 nm / Ta 3 nm. Here, the lower TaO is the NOL for the buffer layer and magnetization free layer, the upper Cu layer is the HCL and underlayer seed layer, the NiFe layer and the CoFe layer are ferromagnetically coupled together to form a magnetization free layer, and the Cu layer is Spacer layer, CoFe layer, NOL, CoFe layer, magnetization pinned layer in which CoFe layers are ferromagnetically coupled, PtMn layer is an antiferromagnetic layer, NiFeCr layer is a magnetic coupling cut layer (decoupling layer), CoFe layer is BCL, The Ta layer is a cap layer. Changes in the material and film thickness of each layer are the same as in the bottom type.
[0100]
Next, the film thickness of the HCL 23 will be described.
[0101]
Current magnetic field H_cuIs provided with an HCL 23 formed in contact with the magnetization free layer 21 to provide a current magnetic field H_cuReduce.
[0102]
At this time, in the NOL-SPSV, the decrease in MR change rate due to the adoption of the ultra-thin magnetization free layer increases the effective film thickness of the magnetization free layer 21 due to the specular electron reflection effect by the NOLs 15 and 25. The film thickness determines the current magnetic field reduction effect with the highest priority. Then, the determination is made to supplement the effect of decreasing the magnetoresistance change rate caused by shunt shunting by the HCL 23.
[0103]
Specifically, the thickness of the HCL 23 is set to a minimum required thickness, so that the shunt of the cap layer 27 in the bottom type can be ignored, for example, if the Ta cap layer 27 having an average thickness of 3 nm is used. Using Cu as the HCL 23, the thickness can be about 0.3 nm or more and about 2 nm or less, and preferably about 0.5 nm or more and about 25 nm or less. The upper limit of the film thickness is because when the film thickness of the HCL 23 is increased, the resistance change rate is reduced due to shunt shunting, and the lower limit of the film thickness is to obtain the effect of the spin filter.
[0104]
On the other hand, the leakage magnetic field H from other ferromagnetic layers applied to the magnetization free layer 21_pIs compensated by the BCL 7 without using the Sy-AF structure for the magnetization pinned layers 13 and 17, but it should be noted that the magnetization of the BCL 7 is not completely fixed in the opposite direction to the magnetization pinned layer.
[0105]
That is, as described above, the magnetization direction of BCL 7 is the current magnetic field H._cu ^BCLAnd leakage magnetic field H from the magnetization pinned layer 13_pin ^BCLIn general, the magnetization direction of the BCL 7 by these two magnetic fields is often not fully oriented in the height direction than the magnetization direction by Sy-AF.
[0106]
Therefore, H in the above equation (2)^BCLIs smaller than the case where the magnetic pinned layers 13 and 17 are completely fixed in the opposite direction. That is, if it is going to have an effect equivalent to the bias compensation in the Sy-AF structure, the BCL 7 requires a magnetic film thickness rather than one magnetic layer of the Sy-AF structure.
[0107]
The difference between the Sy-AF structure and BCL7 is the sense current magnetic field H_cu ^BCLThe smaller the size, the more conspicuous. Conversely, if the sense current is sufficiently large, the difference is small. Further, since the BCL 7 is fixed in the magnetization direction opposite to that of the magnetization pinned layers 13 and 17 due to the leakage magnetic field from the magnetization pinned layers 13 and 17, the larger the magnetic film thickness of the pinned layer, the larger the Sy-AF. The difference with the structure becomes smaller, and vice versa.
[0108]
As a perfect ideal state, when the magnetic film thickness of the magnetization pinned layers 13 and 17 is sufficiently large and the sense current is sufficiently large, if the incomplete difference in magnetization fixation in the height direction of the BCL 7 is considered, The expressions (1) and (2) can be easily satisfied.
[0109]
When analysis was performed using LLG (Landau Lifshits Girbard) micromagnetic simulation, the imperfection of the pin magnetization direction of BCL7 was about 70% to about 95% when compared with Sy-AF. That is, the BCL 7 needs a magnetic film thickness 1.1 to 1.4 times that of one magnetic layer in the Sy-AF structure.
[0110]
The magnetic film thickness of the antiferromagnetic layer-side magnetization pinned layer 13 is about 1.0 nm or more and about 3 nm or less in terms of CoFe (about 1.8 nm or more and about 5.4 nm or less in terms of NiFe). △ t allowed due to leakage magnetic field_pin (△ t_pin= (Ms × t)_pin− (Ms × t)_BCL), Since 0.5 nmT to 2 nmT, the effective pinned layer magnetic film thickness in the height direction by BCL7 is 0.9 nmT to 4.9 nmT.
[0111]
In addition, the film thickness actually required for BCL7 is about 1.1 to 1.4 times the thickness of one magnetic layer of the Sy-AF structure as described above, so the NiFe equivalent film thickness is about 1 nm or more, about 6.9 nm or less, about 0.6 nm or more and about 3.8 nm or less in terms of CoFe.
[0112]
Here, it is assumed that the magnetic film thickness of the antiferromagnetic layer-side magnetization pinned layer 13 can be reduced. However, since it is actually increased when NOL 15 is included, a desirable range is about 1.8 nm or more in terms of NiFe, It is preferably about 4.5 nm or less, about 1 nm or more and about 2.5 nm or less in terms of CoFe.
[0113]
FIG. 3 shows the results of the LLG micromagnetic simulation performed to obtain the optimum value of the BCL film thickness with the film configuration of Example 1.
[0114]
△ t_pin of zero asymmetry [nmT] is Δt when good target (asymmetry) is obtained_pinIs the value of In addition, pinned layer pinning corresponds to an ideal state in which the magnetization of the magnetization pinned layer is completely oriented in one direction in the height direction, and Hua 800 [Oe] and 400 [Oe] are one of the magnetization pinned layers. It shows directional anisotropy, and as the value becomes smaller, it corresponds to a state where it is more likely to be tilted by the leakage magnetic field from the hard film 29 than the ideal state.
[0115]
The track width of the magnetoresistive film 28 determined by the distance between the hard film and the lead electrode is 0.5 mm and the height is 0.3 mm.
[0116]
In FIG. 3, the horizontal axis represents the relative strength of the hard film thickness, and the magnetic film thickness (Ms × t) of the hard film._hardAnd free layer magnetic film thickness (Ms × t)_freeIt is calculated by the ratio of Since an actual head has a bias value different from that of an ideal system, the absolute value on the horizontal axis has little meaning, and is a relative value in a range where Barkhausen noise does not occur in the calculation. The sense current is changed as a parameter.
[0117]
In FIG. 2, the vertical axis is the BCL 7 film thickness when the bias point is the optimum value and the non-target property of the signal waveform becomes zero, and the NiFe equivalent magnetic film thickness (nmT) on the left side. On the right side, the CoFe equivalent film thickness of saturation magnetization 1.8T is shown.
[0118]
As a result, although it depends on the uniaxial anisotropy Hua of the magnetization pinned layers 13 and 17, the preferable range of the film thickness when the BCL 7 is CoT having a saturation magnetization of 1.8T is about 1 nm or more and about 2.5 nm or less. I understand.
[0119]
These ranges are as follows: the thicker the nonmagnetic highly conductive layer HCL23, the thicker the BCL film, the thicker the Hua, the thinner the BCL film, and the smaller the sense current, the BCL film thickness. The optimum condition will shift to the thinner side.
[0120]
【The invention's effect】
Magnetoresistive element having a layer containing oxide, nitride, carbide, or fluoride and having a good bias point, magnetoresistive effect head, magnetic reproducing device having the same, magnetic storage device, and magnetism A resistance detection method for a resistance effect film can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a magnetoresistive effect element according to a first embodiment.
FIG. 2 is an enlarged cross-sectional view for explaining bias point adjustment of the magnetoresistive effect element according to the first embodiment.
FIG. 3 is a diagram showing a calculation result in the first embodiment.
[Explanation of symbols]
7 ... BCL
9 ... Decoupling layer
11 ... Antiferromagnetic layer
13 ... Magnetized pinned layer
15 ... NOL
17 ... Magnetized pinned layer
19: Nonmagnetic spacer layer
21 ... Magnetization free layer
23 ... HCL
25 ... NOL
29 ... Bird bias film
31 ... Lead electrode

Claims (11)

A first ferromagnetic layer comprising a magnetization in a first direction with an applied magnetic field of zero, the magnetization being rotatable under a predetermined applied magnetic field;
A first nonmagnetic layer laminated on the first ferromagnetic layer;
A second ferromagnetic layer formed on the first nonmagnetic layer, wherein the applied magnetic field is zero and retains magnetization in a second direction under the predetermined applied magnetic field;
An antiferromagnetic layer formed between the second ferromagnetic layer and the second nonmagnetic layer and in contact with the second ferromagnetic layer;
A second nonmagnetic layer laminated on the antiferromagnetic layer;
A third ferromagnetic layer formed on the second nonmagnetic layer, the magnetization pinning direction of which is opposite to the second direction and made of a soft magnetic material;
A layer containing an oxide, nitride, carbide, or fluoride formed in the second ferromagnetic layer or between the second ferromagnetic layer and the second nonmagnetic layer; A magnetoresistive effect film, and
A magnetoresistive effect element comprising a pair of electrodes for causing a current to flow through the magnetoresistive effect film so that a direction of a current magnetic field in the third ferromagnetic layer is opposite to the second direction. The direction of the leakage magnetic field applied from the third ferromagnetic layer to the first ferromagnetic layer is applied to the first ferromagnetic layer, the leakage magnetic field from the second ferromagnetic layer, the current 2. The magnetism according to claim 1, wherein the magnetic field is in a direction that cancels the direction of the magnetic field obtained by the sum of the interlayer coupling magnetic fields due to the interlayer coupling between the first ferromagnetic layer and the second ferromagnetic layer. Resistive effect element.   A third nonmagnetic layer containing any one element of Cu, Au, and Ag formed on the surface of the first ferromagnetic layer opposite to the surface in contact with the first nonmagnetic layer; The magnetoresistive effect element according to claim 1, wherein the magnetoresistive effect element is provided.   4. The magnetoresistive effect element according to claim 1, wherein an average film thickness of the first ferromagnetic layer is 3 nm or less. 5.   5. The magnetoresistive effect element according to claim 1, wherein a magnetic film thickness of the third ferromagnetic layer is 1.8 nmT or more and 4.5 nmT or less in terms of a material of saturation magnetization 1T. .   6. The magnetoresistive element according to claim 1, wherein the third ferromagnetic layer contains a CoFe alloy of 50 atomic% or more and an average film thickness of 1 nm to 2.5 nm. .   The magnetoresistive effect element according to any one of claims 1 to 6, wherein an average film thickness of the oxide, nitride, carbide, or fluoride-containing layer is 1 nm or more and 2 nm or less.   A magnetic reproducing head comprising the magnetoresistive effect element according to claim 1.   A magnetic reproducing apparatus comprising the magnetic reproducing head according to claim 8.   A magnetic storage device comprising a plurality of magnetoresistive elements according to claim 1. A first ferromagnetic layer having magnetization in a first direction with an applied magnetic field being zero and capable of rotating the magnetization under a predetermined applied magnetic field, and being laminated on the first ferromagnetic layer A first nonmagnetic layer and a second strong magnetic layer that is stacked on the first nonmagnetic layer and maintains magnetization in a second direction under a state in which the applied magnetic field is zero and the predetermined applied magnetic field. An antiferromagnetic layer formed between the magnetic layer, the second ferromagnetic layer and the second nonmagnetic layer and in contact with the second ferromagnetic layer, and a laminate formed on the antiferromagnetic layer A second nonmagnetic layer, and a third ferromagnetic layer formed on the second nonmagnetic layer, the magnetization pinning direction of which is opposite to the second direction and made of a soft magnetic material; Oxide, nitride, carbon formed in the second ferromagnetic layer or between the second ferromagnetic layer and the second nonmagnetic layer A magnetoresistive film comprising an oxide or a fluoride-containing layer, by passing a current in a direction in which a current magnetic field in the third ferromagnetic layer is opposite to the second direction, A method for detecting a resistance of a magnetoresistive film, comprising detecting a resistance value.

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